Bicycle compounds, their production and use

ABSTRACT

New bicyclic compounds, inclusive of salts thereof, of the formula: ##STR1## wherein R 1  and R 2  are the same or different and each represents hydrogen, hydroxyl or lower alkoxy, R 3  is hydrogen or lower alkyl, R 4  is hydrogen, lower alkyl, amino-lower-alkyl or acylamino-lower-alkyl, R 5  is hydrogen, lower alkyl or aralkyl which may be substituted, R 6  is hydroxyl, lower alkoxy, amino or lower alkylamino, and m and n each means 1 or 2, have inhibitory activities of angiotensin converting enzyme and bradykinin decomposing enzyme, and are useful as antihypertensive agents.

This invention relates to novel bicyclic compounds, which are useful aspharmaceuticals, and a process for producing the same.

As compounds having hypotensive effect due to inhibitory activity toangiotensin converting enzyme, there are known various amino acidderivatives [e.g. Japanese Patent Unexamined Publication (Kokai) Nos.77-116457, 77-136117, 79-12372, 80-38382 and 80-81845, which correspondto U. S. Pat. Nos. 4,105,776, 4,053,651, British Unexamined Pub. No.2000508, European Unexamined Pub. Nos. 9183 and 12401, respectively].The compounds of the present invention are different from these knowncompounds in skeletal structure, and moreover have superior angiotensinconverting enzyme inhibitory and hypotensive activities.

Thus, the present invention provides novel bicyclic compoundsrepresented by the formula: ##STR2## wherein R¹ and R² are the same ordifferent and each represents hydrogen, hydroxyl or lower alkoxy; R³ ishydrogen or lower alkyl; R⁴ is hydrogen, lower alkyl, amino-lower-alkylor acylamino-lower-alkyl; R⁵ is hydrogen, lower alkyl or aralkyl whichmay be substituted; R⁶ is hydroxyl, lower alkoxy, amino or loweralkylamino; and m and n each means 1 or 2, and salts thereof.

Referring to the above formula (I), the lower alkoxy group representedby R¹ or R² includes those containing about 1-4 carbon atoms, such asmethoxy, ethoxy, propoxy, butoxy and isopropoxy. R¹ and R², when theyare adjacent, may form a lower (C₁₋₄) alkylenedioxy, such asmethylenedioxy or ethylenedioxy.

The lower alkyl group represented by R³ includes those containing about1-4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl and tert-butyl.

The lower alkyl group represented by R⁴ includes lower alkyl groupssimilar to those represented by R³. The amino-lower-alkyl grouprepresented by R⁴ includes straight or branched ones containing about1-4 carbon atoms, such as aminomethyl, 1-aminoethyl, 2-aminoethyl,3-aminopropyl, 4-aminobutyl and 3-amino-2-methylpropyl. Theacylamino-lower-alkyl group represented by R⁴ includes those groups inwhich the amino group of the above-mentioned amino-lower-alkyl group isacylated with a carboxylic acid- or carbonate ester-derived acyl group.Said acyl group is, for example, C₂₋₄ alkanoyl (e.g. acetyl, propionyl),benzoyl, C₂₋₄ alkoxycarbonyl (e.g. ethoxycarbonyl) or benzyloxycarbonyl.

Referring to R⁵, the lower alkyl group represented thereby includeslower alkyl groups similar to those represented by R³. The aralkyl grouprepresented by R⁵ includes phenyl-lower (C₁₋₄)-alkyl containing about7-10 carbon atoms, such as benzyl, phenethyl, 3-phenylpropyl,α-methylbenzyl, α-ethylbenzyl, α-methylphenethyl, β-methylphenethyl andβ-ethylphenethyl. The phenyl moiety of said phenyl-lower-alkyl group mayoptionally have 1-3 substituents such as halogen (e.g. fluorine,chlorine, bromine, iodine), C₁₋₄ alkyl (e.g. methyl, ethyl, propyl,butyl), C₁₋₄ alkoxy (e.g. methoxy, ethoxy, propoxy, isopropoxy, butoxy,methylenedioxy), amino, nitro or hydroxyl. Examples of such substitutedphenyl-lower-alkyl group are 2-(4-chlorophenyl)ethyl,2-(4-hydroxyphenyl)ethyl, 2-(4-methoxphenyl)ethyl,2-(3,4-dimethoxyphenyl)ethyl, 2-(3,4,5-trimethoxyphenyl)ethyl,2-(3,4-methylenedioxyphenyl)-ethyl, 2(p-tolyl)ethyl,3,4-dimethoxybenzyl, 3,4-methylenedioxybenzyl, 3,4,5-trimethoxybenzyl,4-ethylbenzyl and 4-chlorobenzyl.

Referring to R⁶, the lower alkoxy represented thereby includes loweralkoxy groups containing about 1-4 carbon atoms, such as methoxy,ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy andtert-butoxy, and the lower alkylamino group includes mono- or di-lower(C₁₋₄)-alkylamino groups, such as methylamino, ethylamino, propylamino,butylamino, dimethylamino and diethylamino.

The salts of compounds (I) include pharmaceutically acceptable salts,for example, inorganic acid salts, such as hydrochloride, hydrobromide,sulfate, nitrate and phosphate; organic acid salts, such as acetate,tartrate, citrate, fumarate, maleate, toluenesulfonate andmethanesulfonate; metal salts, such as sodium, potassium, calcium andaluminum salts; and salts with bases, such as triethylamine, guanidine,ammonium, hydrazine, quinine and cinchonine salts.

In the above-mentioned compounds (I), preferred embodiments are those ofthe formula (I) wherein R¹ and R² independently represent hydrogen,hydroxyl or C₁₋₄ alkoxy, or R¹ and R² jointly form C₁₋₄ alkylenedioxy;R³ is hydrogen or C₁₋₄ alkyl; R⁴ is hydrogen, C₁₋₄ alkyl or amino-C₁₋₄alkyl which is unsubstituted or substituted by acyl of the classconsisting of C₂₋₄ alkanoyl, benzoyl, C₂₋₄ alkoxycarbonyl orbenzyloxycarbonyl; R⁵ is hydrogen, C₁₋₄ alkyl or phenyl-C₁₋₄ alkyl whichis unsubstituted or substituted by 1 to 3 members of halogen, C₁₋₄alkyl, C₁₋₄ alkoxy, amino, nitro and hydroxyl, R⁶ is hydroxyl, C₁₋₄alkoxy, amino or mono- or di-C₁₋₄ alkylamino; and m and n each means 1or 2, and pharmaceutically acceptable salts thereof.

Among the compounds (I), further preferred are compounds wherein R¹ andR² are each hydrogen, R³ is hydrogen, R⁴ is lower (C₁₋₄) alkyl oramino-lower(C₁₋₄)-alkyl, R⁵ is phenethyl, R⁶ is lower(C₁₋₄) alkoxy orhydroxyl, and m and n are each 1, or compounds of the formula: ##STR3##wherein R^(4') is hydrogen or C₁₋₄ alkyl, R^(5') is hydrogen, C₁₋₄ alkylor phenyl-C₁₋₄ alkyl, and R^(6') is hydroxyl or C₁₋₄ alkoxy, and theirpharmaceutically acceptable salts.

Referring to the above formula (I'), the groups in R^(4'), R^(5') andR^(6') correspond to those of R⁴, R⁵ and R⁶ respectively.

A preferable specific embodiment in the present invention isN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycine andits pharmaceutically acceptable salts.

The compounds (I) of the present invention can be produced, for example,by subjecting a compound of the formula: ##STR4## wherein the symbolsare each as above defined, and a compound of the formula: ##STR5##wherein R⁵ and R⁶ are as above defined, to condensation under reductiveconditions.

Said reductive conditions include those reaction conditions used incatalytic reduction using as a catalyst such a metal as platinum,palladium, Raney nickel or rhodium or a mixture thereof with anappropriate carrier; reduction with a metal hydride compound such aslithium aluminum hydride, lithium borohydride, lithium cyanoborohydride,sodium borohydride or sodium cyanoborohydride; reduction with metallicsodium or metallic magnesium and an alcohol; reduction with such a metalas iron or zinc and such an acid as hydrochloric acid or acetic acid;electrolytic reduction and reduction with a reducing enzyme. The abovereaction is usually carried out in the presence of water or an organicsolvent (e.g. methanol, ethanol, ethyl ether, dioxane, methylenechloride, chloroform, benzene, toluene, acetic acid, dimethylformamide,dimethylacetamide). The reaction temperature depends on the means ofreduction employed, but generally temperatures ranging from -20° C. to+100° C. are preferred. The reaction can proceed in a satisfactorymanner at ordinary pressure, but the reaction may also be carried outunder pressure or under reduced pressure according to circumstances.

Those compounds (I) wherein R³ is hydrogen or/and R⁶ is hydroxyl canalso be produced by hydrolysis of the corresponding ester compounds orby catalytic reduction of the corresponding benzyl esters.

The compound (I) can further be produced by subjecting a compound of theformula: ##STR6## wherein Z is a protective group removable byhydrolysis or catalytic reduction and the other symbols are each asabove defined, to hydrolysis or catalytic reduction. The protectivegroup represented by Z in formula (IV) and removable by hydrolysisincludes all sorts of acyl groups and trityl. In particular, such groupsas benzyloxycarbonyl, tert-butoxy carbonyl, trifluoroacetyl and tritylare advantageous for a reaction under relatively mild conditions. Theprotective group represented by Z and removable by catalytic reductionincludes benzyl, diphenylmethyl and benzyloxycarbonyl, among others. Thehydrolysis reaction in this method is carried out in water or an organicsolvent such as methanol, ethanol, dioxane, pyridine, acetic acid,acetone or methylene chlolride, or a mixture thereof. For acceleratingthe reaction, and acid (e.g. hydrochloric, hydrobromic, hydroiodic,hydrofluoric, sulfuric, methanesulfonic, p-toluenesulfonic ortrifluoroacetic acid) or a base (e.g. sodium hydroxide, potassiumhydroxide, potassium carbonate, sodium hydrogen carbonate, sodiumacetate, triethylamine) may be added to the reaction system. Thereaction temperature is usually in the range of about -10° C. to +150°C. The catalytic reduction in this method is carried out in water or anorganic solvent such as methanol, ethanol, dioxane or tetrahydrofuran,or a mixture thereof, in the presence of an appropriate catalyst such asplatinum or palladium-carbon. This reaction is carried out at ordinarypressure or under pressure up to about 150 kg/cm² and at ordinarytemperature or a temperature up to 150° C. Generally, the reaction canproceed sufficiently smoothly at ordinary temperature and at ordinarypressure.

The compounds (I) can also be produced by reacting a compound (II) witha compound of the formula: ##STR7## wherein R⁵ and R⁶ are each as abovedefined and X is halogen or a group or the formula R⁷ SO₂ --O-- in whichR⁷ is lower alkyl, phenyl or p-tolyl. The reaction is carried out bymaintaining both the reactants in an appropriate solvent at atemperature within the range of about -10° C. to about +150° C. Foraccelerating the reaction, such a base as potassium carbonate, sodiumhydroxide, sodium hydrogen carbonate, pyridine or triethylamine may bemade to coexist in the reaction system as a deacidifying agent.

The object compounds (I) of the present invention produced in this waycan be isolated from the reaction mixture by usual means of separationand purification, such as extraction, concentration, neutralization,filtration, recrystallization, column chromatography and/or thin layerchromatography.

Depending on the presence or absence of the substituents represented byR⁴ and R⁵, there may exist two to eight steric isomers of a compound(I). These individual isomers and mixtures thereof naturally fall withinthe scope of the present invention. Such isomers, if desired, can beprepared individually. For example, a single optical isomer of (I) canbe obtained by carrying out the above reaction using a single isomer ofthe starting compound (II) or (IV). When the product is a mixture of twoor more isomers, they can be separated into individual isomers by ausual separation technique, such as salt formation using an opticallyactive acid (e.g. camphor-sulfonic, tartaric or dibenzoyltartaric acid)or an optically active base (e.g. cinchonine, cinchonidine, quinine,quinidine, alphamethylbenzylamine, dehydroabietylamine), a variety ofchromatographic techniques or fractional crystallization. For thosecompounds (I) wherein R⁴ and R⁵ are each other than hydrogen, theisomers respectively having an S configuration generally have morepreferable physiological activities as compared with the correspondingcompounds having an R configuration.

The compounds of the present invention, i.e., the bicyclic compoundsrepresented by formula (I) and pharmaceutically acceptable saltsthereof, exhibit inhibitory activities on angiotensin converting enzyme,bradykinin decomposing enzyme (kininase) and enkephalinase in animals,in particular, mammals (e.g. human, dog, cat, rabbit, guinea pig, rat)and therefore are useful as drugs for diagnosis, prevention or treatmentof hypertension and as analgesic and analgesic-activity-potentiatingagents. The compounds of the present invention are of low toxicity, wellabsorbed even on oral administration and highly stable. Therefore, whenthey are used as the above-mentioned drugs, they can safely beadministered orally or parenterally, per se or in admixture withsuitable pharmaceutically acceptable carriers, excipients or diluents invarious pharmaceutical formulations such as powders, granules, tablets,capsules, injectable solution, etc. While the dosage level generallyvaries depending upon the conditions of the diseases to be treated aswell as the administration route used, for example, in the treatment ofhypertension in adult human, the compounds may be administered orally ata single dose of about 0.02-20 mg/kg, preferably about 0.2-2 mg/kg, orintravenously at about 0.002-2 mg/kg, preferably about 0.02-0.2 mg/kg,about 2 to 5 times per day according to the conditions.

The starting compounds (II) of this invention can easily be prepared,for example, by the process shown by the following reaction scheme:##STR8## In the above formulas, R¹, R², R³, R⁴, m and n are as abovedefined, and C_(bz) is benzyloxycarbonyl.

The process for preparing (II) as shown by the above reaction scheme isnow illustrated in more detail. Firstly, in the step (VI)→(VIII), (VI)and (VII) are reacted in an appropriate solvent to yield a Schiff base,which is then subjected to reduction. An organic solvent such asmethanol, ethanol, dioxane, methylene chloride, chloroform, benzene ortoluene is used as the solvent, and the reaction is conducted generallyat a temperature within the range of about -10° C. to +150° C. Foradvantageous progress of the reaction, a catalyst, such as sulfuric acidor p-toluenesulfonic acid, or a dehydrating agent, such as anhydroussodium sulfate, anhydrous magnesium sulfate or calcium chloride, may beadded to the reaction mixture. It is also possible to make the reactionproceed advantageously by using a water separating device (trap). TheSchiff base obtained is, either in the form of a reaction mixture orafter isolation in a usual manner again added to a solvent and subjectedto reduction. The means of reduction include catalytic reduction usingplatinum or palladium-carbon, for instance, as a catalyst, and a methodusing such a reducing agent as sodium borohydride or sodiumcyanoborohydride.

It is also possible to make the Schiff base formation and reductionproceed simultaneously by allowing such a reducing agent to coexist inthe reaction mixture of (VI) and (VII) from the beginning. In the step(VIII)→(X), (VIII) is reacted with (IX) or a carboxyl-derived functionalderivative thereof. The carboxyl-derived functional derivative ofcompound (IX) includes among others acid halides, such as acid chlorideand acid bromide; acid anhydrides obtainable by removing one mole ofwater from two moles of (IX); mixed anhydrides formed by substitution ofthe hydrogen atom of the carboxyl group in (IX) by ethoxycarbonyl,isobutyloxycarbonyl, benzyloxycarbonyl, etc.; and reactive esters of(IX) derived from 1-hydroxybenzotriazole, N-hydroxyphthalimide,N-hydroxysuccinimide, etc. Generally, the reaction is carried out in anappropriate solvent, which may be of any kind so long as it does notdisturb the reaction. When (IX) is used as it is without converting itto a functional derivative, the reaction is preferably carried out inthe presence of a dehydrating agent such as dicyclohexylcarbodiimide orcarbonyldiimidazole. When an acid halide is used as the functionalderivative, the reaction may also be carried out in the presence of abase such as pyridine, picoline, triethylamine, sodium hydroxide, sodiumhydrogen carbonate or sodium carbonate. Generally, the reactiontemperature is within the range of about -20° C. to about +150° C. Inmost cases, however, the reaction can proceed in a satisfactory mannerat ordinary temperature. The step (X)→(II) consists in removal of theN-protecting group by catalytic reduction. The catalytic reduction iscarried out in water or an organic solvent, such as methanol, ethanol,dioxane, tetrahydrofuran or acetic acid, or a mixture thereof, in thepresence of an appropriate catalyst, such as platinum, palladium-carbonor Raney nickel. This reaction is carried out at ordinary pressure toabout 150 kg/cm² and at ordinary temperature to 150° C. Generally, thereaction can proceed in a satisfactory manner at ordinary temperature.

The invention will be further illustrated in more detail by thefollowing reference examples, embodiment examples, test examples anddosage form examples, which, however, are by no means limitative of thepresent invention.

REFERENCE EXAMPLE 1

Glycine ethyl ester hydrochloride (20 g) is dissolved in a solution of10 g of 2-indanone in 200 ml of methanol, and then 5.0 g of sodiumcyanoborohydride is added portionwise to the solution with ice coolingand stirring. After stirring at room temperature for 2 hours, thereaction mixture is poured into 500 ml of ice water, and the wholemixture is made alkaline with sodium hydrogen carbonate and extractedwith 300 ml of ethyl acetate. The extract is washed with water anddried, the ethyl acetate is distilled off under reduced pressure, 10 mlof 20% ethanolic hydrochloric acid and 200 ml of ethyl ether are addedto the residue, and the mixture is allowed to stand at room temperature.The resulting crystalline precipitate is collected by filtration anddried to give 11 g of N-(indan-2-yl)glycine ethyl ester hydrochloride ascolorless needles melting at 165°-167° C.

REFERENCE EXAMPLE 2

To a solution of 5 g of 2-indanone in 150 ml of methanol is added 15 gof glycine benzyl ester paratoluenesulfonate, and then 5 g of sodiumcyanoborohydride is added portionwise with ice cooling and stirring.Thereafter, the mixture is treated in the same manner as in ReferenceExample 1 to give 6.5 g of N-(indan-2-yl)glycine benzyl esterhydrochloride as colorless prisms melting at 186°-189° C.

REFERENCE EXAMPLE 3

2-Indanone (40 g) is dissolved in 300 ml of methanol, 78 g of glycinetert-butyl ester phosphite and 150 g of water are added, and then 23 gof sodium cyanoborohydride is added over 15 minutes with ice cooling andstirring. The resulting mixture is further stirred at room temperaturefor 4 hours. To the reaction mixture, 400 ml of 20% phosphoric acid isadded portionwise over an hour, 200 ml of water is then added, themixture is stirred for 30 minutes and then extracted with 800 ml ofethyl ether, and the aqueous layer is adjusted to pH 10 with 20% sodiumhydroxide and extracted with 4 portions (500 ml in total) of chloroform.The extract is dried over anhydrous sodium sulfate and then distilledunder reduced pressure. 50 ml of ethanol and then 150 ml of water areadded to the oil obtained, and the mixture is cooled. The crystallineprecipitate is collected by filtration and recrystallized twice fromaqueous ethanol to give 47 g of (indan-2-yl)glycine tert-butyl ester ascolorless prisms melting at 54°-55° C.

REFERENCE EXAMPLE 4

A solution of 22.3 g of N-carbobenzoxy-L-alanine and 14 ml oftriethylamine in 200 ml of tetrahydrofuran is cooled to -10° C., and13.1 ml of isobutyl chlorocarbonate is added dropwise in portions withstirring. After stirring for 30 minutes, a solution of 24.1 g ofN-(indan-2-yl)glycine ethyl ester hydrochloride and 14 ml oftriethylamine in 200 ml of chloroform is added dropwise at -10° C. to-5° C. After standing overnight at room temperature, the reactionmixture is washed in sequence with water, aqueous sodium hydrogencarbonate, 10% hydrochloric acid and water, and dried over anhydroussodium sulfate. The solvent is distilled off under reduced pressure, theresidue is dissolved in 100 ml of methanol, 75 ml of 2N sodium hydroxideis added, and the mixture is stirred at room temperature for 2 hours.Then, the mixture is made acidic with 10% hydrochloric acid to separatethe resulting oil, which is extracted with 500 ml of ethyl acetate. Theextract washed with water and dried, and the solvent is distilled offunder reduced pressure to give 25 g ofN-carbobenzoxy-L-alanyl-N-(indan-2-yl)glycine as an oil. This isdissolved in 50% ethanol and subjected to catalytic reduction in thepresence of 4 g of 10% palladium-carbon. When the hydrogen absorptionhas ceased, the catalyst is filtered off, and the filtrate isconcentrated under reduced pressure. Addition of 50 ml of methanol tothe residue yields 11 g of L-alanyl-N-(indan-2-yl)glycine as colorlessneedles melting at 180°-182° C.

REFERENCE EXAMPLE 5

N-Carbobenzoxy-L-alanine (21.8 g) and 12.3 ml of triethylamine aredissolved in 200 ml of tetrahydrofuran, and 8.5 of ethyl chlorocarbonateis added dropwise at -15° C. with stirring. After the dropping, stirringis continued for 15 minutes, and then a solution of 22 g of(indan-2-yl)glycine tert-butyl ester in 100 ml of chloroform is addeddropwise at -10° C. or below. After stirring at room temperature for anhour, the reaction mixture is poured into 500 ml of water, and thechloroform layer is separated and the chloroform is distilled off. Theresidue is dissolved in 300 ml of ethyl acetate, the solution is washedwith two 50-ml portions of 1N aqueous sodium hydroxide, one 50-mlportion of water, two 50-ml portions of 20% aqueous phosphoric acid andone 50-ml portion of water, in that order, and then dried over anhydrousmagnesium sulfate, and the solvent is distilled off to give 35 g ofN-carbobenzoxy-L-alanyl-N-(indan-2-yl)glycine tertbutyl ester as an oil.This is dissolved in 300 ml of methanol and, after addition of 7 g ofoxalic acid and 3.5 g of 10% palladium-carbon (containing 50% water), issubjected to catalytic reduction at ordinary temperature and ordinarypressure. After the reaction, the catalyst is filtered off, the filtrateis distilled off under reduced pressure, and 500 ml of ethanol is addedto the residue. On cooling, a precipitate forms, which is collected byfiltration and dried to give 21.8 g of L-alanyl-N-(indan-2-yl)glycinetert-butyl ester oxalate melting at 138°-141° C.

[α]_(D) ²² +20.4° (c=1, methanol).

REFERENCE EXAMPLE 6

N-(Indan-2-yl)glycine benzyl ester hydrochloride (6 g) is added to amixture of 300 ml of ethyl acetate and 200 ml of 5% aqueous potassiumcarbonate, followed by vigorous stirring. To the resulting solution isadded dropwise 6 ml of chloroacetyl chloride over 30 minutes with icecooling. Thereafter, stirring is continued for an hour. The ethylacetate layer is then separated, washed with water and dried overanhydrous magnesium sulfate, and the solvent is distilled off underreduced pressure. Addition of ether to the residue gives 6 g ofN-chloroacetyl-N-(indan-2-yl)glycine benzyl ester as colorless scalesmelting at 99.5°-100.5° C.

REFERENCE EXAMPLE 7

N-Chloroacetyl-N-(indan-2-yl)glycine benzyl ester (3 g) and 2 g ofN-benzylglycine ethyl ester are dissolved in 50 ml of methyl ethylketone, 10 g of potassium carbonate is added, and the mixture isrefluxed for 24 hours with stirring. After cooling, the insoluble matteris filtered off, and the filtrate is distilled under reduced pressure togive an oil. This is purified by silica gel column chromatography togive 3 g of N-ethoxycarbonylmethyl-N-benzylglycyl-N-(indan-2-yl)glycinebenzyl ester as an oil.

Infrared (IR) Absorption Spectrum ν_(max) ^(Neat) cm⁻¹ : 1730, 1640.

REFERENCE EXAMPLE 8

By reacting 7 g of N-(indan-2-yl)glycine tert-butyl ester with 8.5 g ofN-(carbobenzoxy)-L-leucine and treating the reaction mixture as inReference Example 5, there is obtained 3.5 g ofL-leucyl-N-(indan-2-yl)glycine tert-butyl ester as colorless amorphouspowder.

REFERENCE EXAMPLE 9

By reacting 8.2 g of N-(indan-2-yl)glycine tert-butyl ester with 13 g ofN.sup.α -tert-butoxycarbonyl-N.sup.ε -carbobenzoxy-L-lysine as inReference Example 5, there is obtained 14 g of N.sup.α-tert-butoxycarbonyl-N.sup.ε -carbobenzoxy-L-lysyl-N-(indan-2-yl)glycinetert-butyl ester as a colorless oil.

NMR(CDCl₃) δ: 1.40, 1.45(18H), 5.05(2H), 7.0-7.3(9H).

IR Spectrum ν_(max) ^(neat) cm⁻¹ : 1700, 1640.

[α]_(D) ²⁴ -14.3° (c=0.9, methanol).

REFERENCE EXAMPLE 10

N.sup.α -tert-Butoxycarbonyl-N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester (5 g)obtained by the procedure of Reference Example 9 is dissolved in 100 mlof 1N solution of hydrogen chloride in ethyl acetate, and the solutionis allowed to stand at room temperature for 6 hours. On adding 500 ml ofpetroleum ether to the reaction mixture, an oily substance separates,which is isolated. The solution layer is concentrated under reducedpressure and again subjected to a similar treatment with hydrogenchloride. The oil fractions obtained are combined, dissolved in 100 mlof ethyl acetate, and washed with 100 ml of 1N aqueous sodium hydroxideand with water. The organic layer is dried over anhydrous magnesiumsulfate and, after addition of 1 g of oxalic acid, the solvent isdistilled off under reduced pressure. Addition of a mixture of ether andpetroleum ether to the residue yields 2.4 g of N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester oxalate ascolorless powder.

Elemental analysis for C₂₉ H₃₉ N₃ O₅.C₂ H₂ O₄.H₂ O--Calcd.: C, 60.28; H,7.02; N, 6.80; Found: C, 59.83; H, 7.01; N, 6.41.

[α]_(D) ²³.5 +17.5° (c=1, methanol).

REFERENCE EXAMPLE 11

In a solution of 13 g of 2-indanone in 100 ml of methanol, there isdissolved 13 g of β-alanine ethyl ester hydrochloride, and, with icecooling and stirring, 6.5 g of sodium cyanoborohydride is addedportionwise. After standing at room temperature overnight, the mixtureis poured into 500 ml of ice water, made alkaline with sodium hydrogencarbonate and extracted with 200 ml of chloroform. The extract is washedwith water, and dried, followed by distilling off chloroform underreduced pressure. To the residue, 10 ml of 20% ethanolic hydrochloricacid and 50 ml of ethyl ester are added successively, and the mixture isallowed to stand at room temperature. The resulting precipitate iscollected by filtration and dried to give 10 g ofN-(indan-2-yl)-β-alanine ethyl ester hydrochloride as colorless scalesmelting at 150°-151° C.

REFERENCE EXAMPLE 12

By reacting 7 g of N-(indan-2-yl)-β-alanine ethyl ester hydrochloridewith 7 g of N-carbobenzoxy-L-alanine and treating the reaction mixtureas in Reference Example 4, there is obtained 5 g ofL-alanyl-N-(indan-2-yl)-β-alanine. Melting point 205°-206° C.

[α]_(D) ²³.5 +16° (c=0.8, 1N HCl).

REFERENCE EXAMPLE 13

In a solution of 20 g of 1,2,3,4-tetrahydro-2-naphthalenone in 200 ml ofmethanol, there is dissolved 23 g of glycine ethyl ester hydrochloride,and 9.0 g of sodium cyanoborohydride is added portionwise with icecooling and stirring. After stirring at room temperature for 2 hours,the reaction mixture is poured into 500 ml of ice water, and the wholemixture is make alkaline with sodium hydrogen carbonate and extractedwith 500 ml of ethyl acetate. The extract is washed with water anddried, the ethyl acetate is distilled off under reduced pressure, 10 mlof 20% ethanolic hydrochloric acid and 200 ml of ethyl ether are addedto the residue, and the mixture is allowed to stand at room temperature.The crystalline precipitate is collected by filtration and dried to give25 g of N-(1,2,3,4-tetrahydronaphthalen-2-yl)glycine ethyl esterhydrochloride as colorless needles melting at 198°-200° C.

REFERENCE EXAMPLE 14

By reacting 13.5 g of N-(1,2,3,4-tetrahydronaphthalen-2-yl)glycine ethylester hydrochloride with 11.6 g of N-carbobenzoxy-L-alanine and treatingthe reaction mixture as in Reference Example 4, there is obtained 7.5 gof L-alanyl-N-(1,2,3,4-tetrahydronaphthalen-2-yl)glycine as colorlessamorphous powder.

IR spectrum ν_(max) ^(Nujol) cm⁻¹ : 1720, 1640.

REFERENCE EXAMPLE 15

By reacting 13 g of (indan-1-yl)glycine ethyl ester hydrochloride with11.6 g of N-carbobenzoxy-L-alanine and treating the reaction mixture asin Reference Example 4, there is obtained 8.0 g ofL-alanyl-N-(indan-1-yl)glycine as colorless amorphous powder.

IR spectrum ν_(max) ^(Nujol) cm⁻¹ : 1730, 1640.

REFERENCE EXAMPLE 16

By reacting 10 g of (5-benzyloxyindan-1-yl)glycine ethyl ester with 8 gof N-carbobenzoxy-L-alanine and treating the reaction mixture as inReference Example 4, there is obtained 5.2 g ofL-alanyl-N-(5-hydroxyindan-1-yl)-glycine as colorless amorphous powder.

REFERENCE EXAMPLE 17

5,6-Dimethoxy-1-indamine hydrochloride (11 g) is suspended in 200 ml ofmethyl ethyl ketone, then 6.9 g of potassium carbonate, 2.0 g ofpotassium iodide and 8.2 g of tert-butyl chlorocarbonate are added, andthe mixture is refluxed for 8 hours. The reaction mixture is poured into500 ml of water and extracted with 200 ml of ethyl acetate, the extractis washed with water and dried, and the ethyl acetate is distilled offunder reduced pressure. The residue is subjected to silica gel columnchromatography and eluted with hexane-acetone (7:3) to give 6.0 g ofN-(5,6-dimethoxyindan-1-yl)glycine tert-butyl ester as an oil. This isdissolved in 50 ml of ethyl ether, 2.0 g of oxalic acid is added, andthe mixture is allowed to stand at room temperature. There is thusobtained 7.3 g of N-(5,6-dimethoxyindan-1-yl)glycine tert-butyl esteroxalate as colorless needles melting at 158°-160° C.

REFERENCE EXAMPLE 18

By reacting 7 g of N-(5,6-dimethoxyindan-1-yl)glycine tert-butyl esteroxalate with 4.8 g of N-carbobenzoxy-L-alanine and treating the reactionmixture as in Reference Example 5, there is obtained 4 g ofL-alanyl-N-(5,6-dimethoxyindan-1-yl)glycine tert-butyl ester oxalate ascolorless amorphous powder.

REFERENCE EXAMPLE 19

A mixture of 143 g of ethyl 3-phenylpropionate, 234 g of ethyl oxalateand 154 ml of 28% sodium ethoxide solution in ethanol is heated on awater bath at a bath temperature of 60°-70° C. for 1.5 hours, whiledistilling off the ethanol under reduced pressure. To the resulting redsyrupy residue is added 1.3 liters of 15 v/v % sulfuric acid. Themixture is boiled under reflux with stirring for 15 hours, and the oillayer is separated, neutralized with 10% sodium hydroxide and extractedwith ethyl acetate. The aqueous layer is made acidic with dilutedsulfuric acid. The resulting oil is extracted with ethyl acetate, washedwith water and dried. Removal of the ethyl acetate by distillation underreduced pressure gives 130 g of 2-oxo-4-phenylbutyric acid as an oil.

REFERENCE EXAMPLE 20

2-Oxo-4-phenylbutyric acid (130 g) is added to a mixture of 650 ml ofethanol and 13 ml of concentrated sulfuric acid, and the whole mixtureis refluxed for 5 hours. The reaction mixture is concentrated toapproximately half the original volume, and then diluted with 500 ml ofwater. The resulting oil is collected and, the aqueous layer isextracted with ethyl acetate. The extract and the oil are combined anddried, and the solvent is distilled off under reduced pressure. Theresidue is distilled under reduced pressure to give 113 g of ethyl2-oxo-4-phenylbutyrate as a colorless oil boiling at 135°-141° C./3mmHg.

REFERENCE EXAMPLES 21-27

Compounds shown in Table 1 can be prepared from the respectivelycorresponding starting compounds by a similar manner to ReferenceExamples 19 and 20.

                  TABLE 1                                                         ______________________________________                                         ##STR9##                                                                     Ref. Ex.                                                                      No.    R'     R"            Boiling Point                                     ______________________________________                                        21     H      CH.sub.3      108-112° C./0.5 mmHg                       22     H      (CH.sub.2).sub.2 CH.sub.3                                                                   105-118° C./1 mmHg                         23     H                                                                                     ##STR10##    132-135° C./3 mmHg                         24     H      (CH.sub.2).sub.3 CH.sub.3                                                                   145-150° C./4 mmHg                         25     H                                                                                     ##STR11##    120-132° C./0.5 mmHg                       26     Cl     CH.sub.2 CH.sub.3                                                                           125-135° C./1 mmHg                         27     CH.sub.3                                                                             CH.sub.2 CH.sub.3                                                                           120-130° C./1 mmHg                         ______________________________________                                    

REFERENCE EXAMPLE 28

Piperidine (7.5 ml) is added to a solution of 99.6 g of veratrumaldehyde and 124.8 g of malonic acid in 240 ml of pyridine, and themixture is heated at 80°-85° C. for an hour and further at 110°-115° C.for 3 hours. After cooling, the reaction mixture is poured into a largeamount of water, and the resulting crystalline precipitate is collectedby filtration. The crystals are dissolved in diluted aqueous sodiumhydroxide. The solution is made acidic with hydrochloric acid to give 70g of 3,4-dimethoxycinnamic acid as needles melting at 182°-183° C. 35 gof these crystals are dissolved in 500 ml of ethanol, and the solutionis saturated with gaseous hydrogen chloride and allowed to stand at roomtemperature overnight. The crystals obtained by distilling off theethanol are dissolved in ethyl acetate. The solution is washed withdiluted aqueous sodium hydrogen carbonate and with water, and dried. Thecrystals obtained by distilling off the ethyl acetate and recrystallizedfrom ethanol to give 65 g of ethyl 3,4-dimethoxycinnamate as scalesmelting at 53°-55° C. 34 g of these crystals are dissolved in 300 ml ofethanol, 10 g of 5% palladium-carbon is added to the solution, and themixture is shaken in a hydrogen atmosphere at room temperature. After 3hours, the catalyst is filtered off, and the filtrate is concentrated togive 34 g of ethyl 3,4-dimethoxyphenylpropionate as an oil. A solutionof 34.1 g of this oil in 43 g of diethyl oxalate is added to a sodiumethoxide solution (prepared from 3.8 g of metallic sodium and 150 ml ofethanol) at 60° C. with stirring. After completion of the addition,stirring is continued at 70°-75° C. for further 3 hours. The ethanol isdistilled off under reduced pressure, 200 ml of water is added to theresidue, and the mixture is washed with ethyl acetate. The aqueous layeris made acidic with hydrochloric acid and then extracted with ethylacetate. The ethyl acetate layer is washed with water, dried andconcentrated to give 27 g of ethyl2-oxo-3-ethoxycarbonyl-4-(3,4-dimethoxyphenyl)butyrate as an oil. 26 gof this oil is dissolved in a mixture of 80 ml of dimethyl sulfoxide and8 ml of water. To the solution is added 6.3 g of sodium chloride, andthe mixture is stirred at 120° C. for 2 hours. After cooling, a largeamount of water is added, and the mixture is extracted with ethylacetate. The extract is washed with water, dried and concentrated togive crystals. Recrystallization from ether yields 15 g of ethyl2-oxo-4-(3,4-dimethoxyphenyl)butyrate ad pillars melting at 85°-87° C.

REFERENCE EXAMPLE 29

Proceeding as in Reference Example 28, there is obtained ethyl4-(p-benzyloxyphenyl)-2-oxobutyrate as a yellow oil from thecorresponding starting material.

NMR Spectrum (CDCl₃) δ: 1.3(t, 3H), 2.7-3.3(m, 4H), 4.3 (q, 2H), 5.0(s,2H), 6.7-7.4(m, 9H).

In the above NMR data, s means a singlet, d a doublet, t a triplet, q aquartet, m a multiplet, and Ph a phenyl group. (Hereinafter the sameshall apply.)

REFERENCE EXAMPLE 30

2-Oxo-4-phenylbutyric acid (9 g) is dissolved in 100 ml of benzene, and10 g of phosphorus pentachloride is added thereto portionwise with icecooling. After stirring at room temperature for an hour, a solution of10 g of butylamine in 20 ml of tetrahydrofuran is added dropwise to thebenzene solution. The reaction mixture is stirred at room temperaturefor 30 minutes and poured into 100 ml of ice water. The mixture isextracted with ethyl acetate, the extract is washed with water anddried, and the ethyl acetate is distilled off under reduced pressure.The residue is subjected to silica gel column chromatography by the useof hexane-acetone (7:3) as the eluent to give 6.0 g ofN-butyl-2-oxo-4-phenylbutylamide as a slightly yellow oil.

NMR Spectrum (CDCl₃) δ: 0.90(3H, m, CH₃), 1.20-1.50(4H, m),2.70-3.40(5H, m), 7.20(5H, s, Ph).

EXAMPLE 1

To a solution of 1.0 g of L-alanyl-N-(indan-2-yl)-glycine and 6.0 g ofethyl 2-oxo-4-phenylbutyrate in 200 ml of ethanol, there is added 8 g ofmolecular sieve, and the mixture is stirred at room temperature for anhour. Then, 1.0 g of sodium cyanoborohydride is added. After standingovernight, the reaction mixture is concentrated under reduced pressure,the residue is adjusted to pH 9.0 with 10% sodium hydroxide, and theinsoluble matter is removed by extraction with ethyl ether. The aqueoussolution is adjusted to pH 4 with 10% hydrochloric acid and extractedwith two 200-ml portions of ethyl acetate. The extract is washed withwater and dried over sodium sulfate, and the solvent is distilled offunder reduced pressure. The residue is dissolved in 2 ml of 20%ethanolic hydrochloric acid, 100 ml of ethyl ether is then added, andthe mixture is allowed to stand at room temperature to give 0.4 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride melting at 168°-170° C.

EXAMPLE 2

L-Alanyl-N-(indan-2-yl)glycine tert-butyl ester oxalate (21 g) isdissolved in 200 ml of ethanol. To the solution 4.1 g of sodium acetate,10 ml of acetic acid, 25 g of ethyl 2-oxo-4-phenylbutyrate and 25 g ofmolecular sieve 3A are added in sequence. Thereafter, 30 g of Raneynickel suspended in 100 ml of ethanol is added with ethanol, andcatalytic reduction is carried out under ordinary temperature andordinary pressure. When the absorption of hydrogen has cased, thesupernatant is separated by decantation, and the precipitate is washedtwo or three times with ethanol. The supernatant and the washings arecombined and concentrated under reduced pressure. The residue isdissolved in 500 ml of ethyl acetate, and the solution is washed withaqueous sodium hydrogen carbonate and filtered with 30 g of diatomaceousearth. The ethyl acetate layer is separated from the filtrate, washedwith water and dried over anhydrous magnesium sulfate, and the solventis distilled off under reduced pressure to give 24 g ofN-(1-ethoxycarbonyl- 3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester as a slightly yellow, viscous oil.

IR Spectrum ν_(max) ^(Neat) cm⁻¹ : 1730(ester), 1640(amide).

NMR Spectrum (CDCl₃) δ: 1.27(3H, t, CH₃), 1.40(9H, s, CH₃ ×3),1.8-2.2(3H, m, CH₃), 2.6-4.5(10H, m), 3.8-3.9(2H, m, CH₂), 4.2(2H, q,CH₂), 4.9(1H, t, CH), 7.1-7.4(9H, m, Ph).

EXAMPLE 3

The N-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester obtained in Example 2 is subjected to columnchromatography using 700 g of silica gel and eluted with benzene,benzene-acetone (10:1 to 4:1) and methanol-benzene (1:9) to give twofractions. Each fraction is further subjected to column chromatographyusing 400 g of silica gel and purified by the above procedure. The firstfraction gives 2 g ofN-[1-(R)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester as a colorless viscous oil.

[α]_(D) ²² -16.4° (c=1, methanol).

On the other hand, the second fraction gives 16.5 g ofN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester as a colorless viscous oil.

[α]_(D) ²² -12.6° (c=1, methanol).

EXAMPLE 4

5 g ofN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester obtained in Example 3 is dissolved in 5 ml of aceticacid, 20 ml of 25% hydrobromic acid in acetic acid is added to thesolution, and the mixture is shaken for 10 minutes. The crystals whichprecipitate on addition of 300 ml of ethyl ether are collected byfiltration to give 5 g ofN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinehydrobromide as colorless crystals melting at 180°-183° C.

[α]_(D) ²⁰ +15.6° (c=1.4, methanol).

EXAMPLE 5

By usingN-[1-(R)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester obtained in Example 3 and treating as in Example 4,there can be obtainedN-[1-(R)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinehydrobromide as colorless crystals melting at 150°-155° C.

[α]_(D) ²⁰ -20.2° (c=1, methanol).

EXAMPLE 6

To a mixture of 500 ml of ethyl acetate, 33 g of sodium hydrogencarbonate and 500 ml of water is added 16.2 g ofN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinehydrobromide prepared by the procedure of Example 4. After stirring tocomplete dissolution, the solution was adjusted to pH 4 with 1Nhydrochloric acid. The ethyl acetate layer is separated, washed withwater, dried and, after addition of 20 ml of 7N ethanolic hydrochloricacid, concentrated under reduced pressure. To the residue are added 250ml of ethyl ether and 250 ml of petroleum ether, and the resultingprecipitate is collected by filtration to give 11 g ofN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride as colorless crystals.

Recrystallization from a mixture of acetone and 1N hydrochloric acidaffords colorless plates melting at 166°-170° C. with decomposition.

[α]_(D) ²² +18.5° (c=1, methanol).

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1740(COOC₂ H₅), 1705(COOH), 1640(CO--N).

EXAMPLE 7

L-Alanyl-N-(indan-2-yl)glycine tert-butyl ester oxalate (4.1 g) isdissolved in 40 ml of ethanol, then 0.85 g of sodium acetate, 2 ml ofacetic acid, 5 g of propyl 2-oxo-4-phenylbutyrate and 5 g of molecularsieve 3A are added, thereafter a suspension of 6 g of Raney nickel in 20ml of ethanol is added, and catalytic reduction is carried out atordinary temperature and ordinary pressure. When the hydrogen absorptionhas ceased, the supernatant is separated by decantation. The precipitateis washed two or three times with ethanol. The supernatant and thewashings are combined, and the solvent is distilled off under reducedpressure. The residue is shaken with 100 ml of ethyl acetate and aqueoussodium hydrogen carbonate. Filtration with 10 g of diatomaceous earth,separation of the ethyl acetate layer of the filtrate, washing withwater, drying and removal of solvent by distillation giveN-(1-propoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)-glycinetert-butyl ester as a slightly yellow, viscous oil. To this are added 3ml of acetic acid and 12 ml of 25% hydrobromic acid solution in aceticacid, and the mixture is shaken occasionally for 15 minutes so as tomake the reaction proceed. On adding 150 ml of ethyl ether, crystallineprecipitate forms, which is collected by filtration to give 3.4 g ofN-(1-propoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrobromide as colorless crystals. They are added to a mixture of 70 mlof water and 70 ml of ethyl acetate, and the mixture is stirred,neutralized with sodium hydrogen carbonate and then adjusted to pH 3-4with 10% hydrochloric acid. The ethyl acetate layer is separated, driedover anhydrous magnesium sullfate, and made acidic with ethanolichydrochloric acid. The solvent is distilled off, and 150 ml of ethylether is added to the residue. After allowing the mixture to stand for10 minutes, the resulting crystalline precipitate is collected byfiltration to give 1.7 g ofN-(1-propoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride melting at 147°-150° C. with decomposition.

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1740(ester), 1710(COOH),1640(CO--N).

EXAMPLE 8

The same procedure as Example 7, excepting the use of butyl2-oxo-4-phenylbutyrate in place of propyl 2-oxo-4-phenylbutyrate, givesN-(1-butoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride melting at 154°-156° C. with decomposition.

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1740(ester), 1700(COOH),1640(CO--N).

EXAMPLE 9

The same procedure as Example 7, excepting the use of isopropyl2-oxo-4-phenylbutyrate in place of propyl 2-oxo-4-phenyl-butyrate, givesN-(1-isopropoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride melting at 150°-153° C. with decomposition.

EXAMPLE 10

The same procedure as Example 7, excepting the use of isobutyl2-oxo-4-phenylbutyrate in place of propyl 2-oxo-4-phenylbutyrate, givesN-(1-isobutoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride melting at 148°-149° C. with decomposition.

EXAMPLE 11

The same procedure as Example 7 using methyl 2-oxo-4-phenylbutyrate inplace of propyl 2-oxo-4-phenylbutyrate and methanol as the solvent inplace of ethanol, givesN-(1-methoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride as colorless needles melting at 163°-165° C. withdecomposition.

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1750(COOCH₃), 1705(COOH),1640(CO--N).

EXAMPLE 12

The same procedure as Example 7, excepting the use of ethyl4-(4-chlorophenyl)-2-oxobutyrate in place of propyl2-oxo-4-phenylbutyrate, givesN-[1-ethoxycarbonyl-3-(4-chlorophenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride.

Melting point 163°-168° C. (decomposition).

[α]_(D) ²³ +28.1° (c=1, methanol).

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1740, 1710, 1640.

EXAMPLE 13

The same procedure as Example 7, excepting the use of ethyl2-oxo-4-(p-tolyl)butyrate in place of propyl 2-oxo-4-phenylbutyrate,givesN-[1-ethoxycarbonyl-3-(p-tolyl)-propyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride.

Melting point 160°-163° C. (decomposition).

[α]_(D) ²³ +22.2° (c=1, methanol).

IR Spectrum ν_(max) ^(Nujol) cm⁻¹ : 1740, 1710, 1640.

EXAMPLE 14

To 100 ml of ethanol, there are added 3 g ofL-alanyl-N-(indan-2-yl)glycine tert-butyl ester oxalate, 0.75 g ofsodium acetate, 1.5 g of acetic acid, 5 g of molecular sieve 3A and 5 gof ethyl 4-(4-benzyloxyphenyl)-2-oxobutyrate, and catalytic reduction iscarried out using Raney nickel as catalyst. When the hydrogen absorptionhas ceased, the catalyst is removed, and catalytic reduction is furthercarried out using palladium-carbon as catalyst. The catalysts isfiltered off and the solvent is distilled off under reduced pressure togiveN-[1-ethoxycarbonyl-3-(p-hydroxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester as oil. This oil is converted by the reaction procedureas used in Example 4 toN-[1-ethoxycarbonyl-3-(4-hydroxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinehydrobromide, which is further converted to the hydrochloride by theprocedure of Example 6. There is thus obtained 0.65 g ofN-[1-ethoxycarbonyl-3-(4-hydroxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride as colorless crystals melting at 126°-130° C. withdecomposition.

[α]_(D) ²⁴ +17.7° (c=1, methanol).

Mass Spectrum m/e: 450(M⁺ -HCl-H₂ O), 335, 334, 331, 330, 284, 215, 214,169, 168, 133, 129, 120, 117, 116, 107.

EXAMPLE 15

L-Alanyl-N-(indan-2-yl)glycine (3.5 g) is suspended in a mixture of 30ml of ethanol and 20 ml of water, and to the suspension is added 15 g ofethyl 2-oxo-4-(3,4-dimethoxyphenyl)butyrate. With stirring at roomtemperature, a solution of 1.4 g of sodium cyanoborohydride in 10 ml ofethanol is added dropwise over about 3 hours. After stirring for anhour, the reaction mixture is concentrated, water is added, and theinsoluble matter is removed by extraction with ether. On adjusting theaqueous layer to pH 4 with diluted hydrochloric acid, an oil separates,which is extracted with ethyl acetate. The ethyl acetate layer is washedwith water, dried and concentrated under reduced pressure. On addingfirst 2 ml of 4N hydrochloric acid-ethanol solution and then 300 ml ofether to the residue, an oily substance separates. The ether is removedby decantation, and the oil is further washed with ether by the sameprocedure, whereby the oil turns into powder. This powder iscrystallized by treatment with dichloromethaneether and recrystallizedfrom the same mixed solvent to give 0.4 g ofN-[1-(S)-ethoxycarbonyl-3-(3,4-dimethoxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride as crystals melting at 138°-140° C. with decomposition.

[α]_(D) ²² +34° (c=0.5, ethanol).

EXAMPLE 16

L-Alanyl-N-(indan-2-yl)glycine (1.0 g) and 6.0 g of phenylpyruvic acidare dissolved in 50 ml of 70% aqueous methanol, and the pH is adjustedto 7.0 with aqueous potassium hydroxide. Sodium cyanoborohydride (1.0 g)is added to this solution. After allowing the mixture to stand at roomtemperature overnight, the solvent is distilled off under reducedpressure, the residue is dissolved in 2 ml of water, made adsorbed on aDowex 50 (H⁺) [trade name of ion-exchange resin] column and eluted with2% pyridine. The solvent is distilled off under reduced pressure, theresidue is purified by silica gel column chromatography usingacetonitrile-methanol (4:1) as the developer to give 0.3 g ofN-(1-carboxy-2-phenylethyl)-L-alanyl-N-(indan-2-yl)glycine as colorlesspowder.

Elemental Analysis for C₂₃ H₂₆ N₂ O₅.HCl-- Calcd.: C, 61.81; H, 6.09; N,6.27; Found: C, 61.43; H, 6.08; N, 6.61.

NMR Spectrum (D₂ O) δ: 1.20-1.60(3H, CH₃), 2.80-4.02(10H),4.90-5.30(1H), 7.10-8.40(10H, Ph).

Mass Spectrum m/e: 392(M-H₂ O).

EXAMPLE 17

By using 1.0 g of L-alanyl-N-(indan-2-yl)glycine, 6.0 g of 2-oxo-butyricacid and 1.0 g of sodium cyanoborohydride in a similar procedure to thatof Example 1, there can be obtained 0.4 g ofN-(1-carboxypropyl)-L-alanyl-N-(indan-2-yl)glycine as colorless powder.

Elemental analysis for C₁₈ H₂₄ N₂ O₅ -- Calcd.: C, 62.05; H, 6.94; N,8.04; Found: C, 61.97; H, 7.58N, 7.46.

NMR Spectrum (D₂ O) δ: 1.00(3H, J=6 Hz, CH₃), 1.25-1.50(3H, --CH₃),3.00-3.85(10H), 5.10-5.20(1H), 7.28(4H, Ph).

Mass Spectrum m/e: 330(M--H₂ O).

EXAMPLE 18

N-(N'-Ethoxycarbonylmethyl-N'-benzylglycyl)-N-(indan-2-yl)glycine benzylester (3 g) is dissolved in 100 ml of ethanol, and catalytic reductionis carried out at ordinary temperature and pressure using 5%palladium-carbon as catalyst. After absorption of 2 equivalents ofhydrogen, the reaction mixture is filtered to remove the catalyst. Theethanol is distilled off under reduced pressure to give an oilysubstance. Addition of ethanolic hydrochloric acid with 100 ml of etherto the oily substance givesN-(N'-ethoxycarbonylmethylglycyl)-N-(indan-2-yl)glycine hydrochloride ascolorless powder.

Elemental analysis for C₁₇ H₂₂ N₂ O₅.HCl.1/2H₂ O-- Calcd.: C, 53.65; H,6.37; N, 7.38; Found: C, 53.63; H, 6.87; N, 7.18.

Mass Spectrum m/e: 316(M-3/2H₂ O-HCl).

EXAMPLE 19

N-(1-(S)-Ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrochloride (1.2 g) is dissolved in 30 ml of methanol. To the solutionis added 5 ml of 2N aqueous sodium hydroxide. After stirring at roomtemperature overnight, the reaction mixture is concentrated underreduced pressure, and 30 ml of water is added. On adjusting the pH to5-6 with diluted hydrochloric acid, an oil separates, which is extractedwith ethyl acetate. The ethyl acetate layer is washed with water anddried, and the solvent is distilled off under reduced pressure. Methanol(5 ml) is added to the residue, and the solution is allowed to stand.There is obtained 0.6 g ofN-(1-(S)-carboxyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycine ascrystals melting at 140°-142° C.

[α]_(D) ²² +26° (c=0.6, 1% HCl).

EXAMPLE 20

N-[1-Ethoxycarbonyl-3-(3,4-dimethoxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride (1.1 g) is dissolved in 30 ml of methanol. To the solutionis added 5 ml of 2N aqueous sodium hydroxide. After stirring for 4hours, the reaction mixture is concentrated, and 30 ml of water isadded. On adjusting the pH to about 5 with diluted hydrochloric acid, anoily substance separates, which is extracted with ethyl acetate. Theextract is washed with water, dried and concentrated. Methanol (4 ml) isadded to the residue, and the mixture is allowed to stand. There isobtained 60 mg ofN-[1-carboxy-3-(3,4-dimethoxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycineas crystals melting at 160°-165° C. with decomposition.

EXAMPLE 21

L-Leucyl-N-(indan-2-yl)glycine tert-butyl ester (3.5 g) is dissolved in50 ml of ethanol, and 3.5 g of ethyl 2-oxo-4-phenylbutyrate, 1.5 g ofsodium acetate, 3.5 g of acetic acid, 7.0 g of molecular sieve 3A and5.0 g of Raney nickel are added, and catalytic reduction is carried outunder ordinary temperature and pressure. After absorption of thetheoretical amount of hydrogen, the catalyst is filtered off, and thefiltrate is concentrated under reduced pressure. To the residue, 100 mlof water and 2 g of sodium hydrogen carbonate are added, and the mixtureis extracted with 200 ml of ethyl acetate. After washing the extractwith water and drying, the ethyl acetate is distilled off under reducedpressure, and 20 ml of acetic acid and 5 ml of 25% hydrobromic acidsolution in acetic acid are added to the residue. After stirring at roomtemperature for 10 minutes, 100 ml of ether is added, and the resultingoil layer is separated and washed with ethyl ether to giveN-(1-ethoxycarbonyl-3-phenylpropyl)-L-leucyl-N-(indan-2-yl)-glycinehydrobromide. This is suspended in 10 ml of water, the suspension ismade alkaline with sodium hydrogen carbonate, and the insoluble matteris extracted with ethyl ether. The aqueous layer is adjusted to pH 4.0with 10% hydrochloric acid, and extracted with 200 ml of ethyl acetate.The extract is washed with water and dried over magnesium sulfate, 1 mlof ethanolic hydrochloric acid is added, and the ethyl acetate isdistilled off under reduced pressure. On adding 200 ml of ethyl ester tothe residue and allowing the mixture to stand at room temperature, thereis yielded 0.8 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-leucyl-N-(indan-2-yl)glycinehydrochloride as colorless amorphous powder.

NMR Spectrum (d₆ -DMSO) δ: 0.93(6H, d, J=3 Hz, CH(CH₃)₂), 1.30(3H, t,J=7 Hz, CH₃), 2.90-3.20(4H, m, CH₂), 3.90(2H, s, CH₂), 4.00-4.35(3H, m),7.20(4H, s, Ph), 7.30(5H, s, Ph).

Mass Spectrum m/e: 476, 431, 361, 315, 171.

EXAMPLE 22

N.sup.ε -Carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl esteroxalate (3.5 g) is dissolved in 20 ml of methanol, and 1 g of sodiumacetate, 1.2 g of acetic acid, 8 g of molecular sieve and 15 g of ethyl2-oxo-4-phenylbutyrate are added. To this mixture is added dropwise withstirring a solution of 3.3 g of sodium cyanoborohydride in 30 ml ofmethanol over 2 hours. 3 g of sodium cyanoborohydride is further added,and the mixture is stirred for 3 hours. After addition of 200 ml of 25%aqueous phosphoric acid, the reaction mixture is extracted with two200-ml portions of ethyl acetate. The extract is washed with 0.5Naqueous sodium hydroxide and with water, and dried over anhydrousmagnesium sulfate. The ethyl acetate is distilled off under reducedpressure, and the oil thus obtained is separated and purified by silicagel column chromatography (acetone-benzene (1:12 to 1:5)). The firstfraction gives 1.1 g of N.sup.α-[1-(R)-ethoxycarbonyl-3-phenylpropyl]-N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester as an oil.

Elemental analysis for C₄₁ H₅₃ N₃ O₇ Calcd.: C, 70.36; H, 7.63; N, 6.00;Found: C, 69.89; H, 7.64; N, 5.76.

[α]_(D) ²⁴ =-4.5° (c=1, methanol).

The second fraction gives 1 g of N.sup.α-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester as an oil.

Elemental analysis for C₄₁ H₅₃ N₃ O₇ Calcd.: C, 70.36; H, 7.63; N, 6.00;Found: C, 70.28; H, 7.51; N, 5.93.

[α]_(D) ²⁴ =-8.2° (c=1, methanol).

IR Spectrum ν_(max) ^(neat) cm⁻¹ : 3300(NH), 1720(C=0), 1630(C=0).

EXAMPLE 23

N.sup.α -[1-(R)-Ethoxycarbonyl-3-phenylpropyl]-N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester (1 g) isdissolved in 2 ml of acetic acid. To the solution, 8 ml of 25%hydrobromic acid solution in acetic acid is added, and the mixture isallowed to stand at room temperature for 30 minutes. On adding 200 ml ofether and 100 ml of petroleum ether to the reaction mixture, acrystalline precipitate forms. This is collected by filtration andrecrystallized from a mixture of methanol and ethyl ehter to give 0.8 gof N.sup.α-[1-(R)-ethoxycarbonyl-3-phenylpropyl]-L-lysyl-N-(indan-2-yl)glycinedihydrobromide melting at 128°-133° C. with decomposition.

[α]_(D) ²⁴ =-11.6° (c=1, methanol)

EXAMPLE 24

By a procedure similar to that described in Example 23, there isobtained 0.6 g of N.sup.α-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-lysyl-N-(indan-2-yl)glycinedihydrobromide from 0.9 g of N.sup.α-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-N.sup.ε-carbobenzoxy-L-lysyl-N-(indan-2-yl)glycine tert-butyl ester.

Melting point: 160°-165° C. (decomposition).

[α]_(D) ²⁴ +18.0° (c=1, methanol).

EXAMPLE 25

By reacting L-alanyl-N-(indan-2-yl)glycine tert-butyl ester oxalate (2.0g) with N-butyl-2-oxo-4-phenylbutyrylamide (4.0 g) in a similar mannerto that of Example 2, there is obtainedN-(1-butylaminocarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester (0.5 g) as colorless oil.

NMR Spectrum (CDCl₃): 1.90 (3H, m, CH₃), 1.40-1.55(16H, m),2.60-3.49(8H, m, CH₂), 3.70-3.95(2H, m), 7.20(4H, s, Ph), 7.30(5H, s,Ph).

EXAMPLE 26

Use ofN-(1-butylaminocarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinetert-butyl ester (0.5 g) as a reactant in a similar manner to that ofExample 4, givesN-(1-butylaminocarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycinehydrobromide as colorless amorphous powder.

NMR Spectrum (d⁶ -DMSO) δ: 0.8-1.0(3H, m, CH₃), 1.2-1.55 (7H, m, CH₃+CH₂ x2), (1.90-2.25(2H, m, CH₂), 2.40-2.60(2H, m, CH₂), 2.95-3.30(6H,m, CH₂), 4.80-5.0(1H, m, CH), 7.10-7.30(9H, m, Ph).

EXAMPLE 27

L-Alanyl-N-(indan-2-yl)-β-alanine (2.0 g) is dissolved in a mixture of20 ml of water and 100 ml of ethanol, 10 g of ethyl2-oxo-4-phenylbutyrate is added, and a solution of 0.94 g of sodiumcyanoborohydride in 20 ml of ethanol is added dropwise over 2 hours. Themixture is stirred at room temperature for 3 hours and then adjusted topH 4.0 with 10% hydrochloric acid, and the ethanol is distilled offunder reduced pressure. The residue is extracted with 200 ml of ethylacetate, washed with water and dried, and the ethyl acetate is distilledoff under reduced pressure. The residue is dissolved in 2 ml of 20%ethanolic hydrochloric acid, 100 ml of ethyl ether is added, and themixture is allowed to stand at room temperature. Thus is obtained 1.2 gof N-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)-β-alaninehydrochloride as colorless amorphous powder.

NMR Spectrum (d₆ -DMSO) δ: 1.30(3H, t, J=7.5 Hz), 1.40(3H, d, J=4.5 Hz),2.65-3.00(4H, m, CH₂), 3.20-3.40(4H, m, CH₂), 4.25(2H, q, J=7.5 Hz,CH₂), 7.20(4H, s, Ph), 7.30(5H, s, Ph).

EXAMPLE 28

L-Ananyl-N-(1,2,3,4-tetrahydrophthalen-2-yl)glycine (3.0 g) is dissolvedin 200 ml of ethanol, 15 g of ethyl 2-oxo-4-phenylbutyrate and 12 g ofmolecular sieve 3A are added, and the mixture is stirred at roomtemperature for 30 minutes. Thereafter, a solution of 1.3 g of sodiumcyanoborohydride in 50 ml of ethanol is added dropwise over 6 hours, andstirring is further continued for 2 hours. The insoluble matter isfiltered off, and the filtrate is concentrated to dryness under reducedpressure. Water (50 ml) is added to the residue, the mixture is madealkaline with sodium hydrogen carbonate, and the insoluble matter isremoved by extraction with ethyl ether. The aqueous layer is adjusted topH 4.0 with 10% hydrochloric acid and then extracted with 200 ml ofethyl acetate. The extract is washed with water and dried, 1 ml of 20%alcoholic hydrochloric acid is added, and the ethyl acetate is distilledoff under reduced pressure. Ethyl ether (100 ml) is added to theresidue, and the mixture is allowed to stand at room temperature to give1.5 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(1,2,3,4-tetrahydronaphthalen-2-yl)glycinehydrochloride as colorless amorphous powder.

NMR Spectrum (d₆ -DMSO) δ: 1.30(3H, t, J=7 Hz, CH₃), 1.40(3H, d, J=6 Hz,CH₃), 1.70-2.30(5H, m, CH₂), 2.80-3.05(7H, m, CH₂), 4.00(2H, s, CH₂),4.30(2H, q, J=7 Hz, CH₂), 7.10 (4H, s, Ph), 7.30(5H, s, Ph).

Mass Spectrum m/e: 448(M-HCl-H₂ O), 344, 319, 168.

EXAMPLE 29

By reacting 3 g of L-alanyl-N-indan-1-yl)glycine with 15 g of ethyl2-oxo-4-phenylbutylate and treating the reaction mixture as in Example28, there is obtained 1.2 g ofN-(1-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-1-yl)glycinehydrochloride as colorless amorphous powder.

NMR Spectrum (d₆ -DMSO) δ: 1.20-1.45(3H, m, CH₃), 1.55-1.65(3H, m, CH₃),2.70-3.05(4H, m, CH₂), 4.00(2H, s, CH₂), 4.40(2H, q, J=7 Hz, CH₂),4.80-5.00(1H, m, ##STR12## 7.30(9H, s, Ph).

Mass Spectrum m/e: 434(M-HCl--H₂ O), 258, 244, 180

EXAMPLE 30

By reacting 3 g of L-alanyl-N-(5-hydroxyindan-1-yl)glycine with 15 g ofethyl 2-oxo-4-phenylbutylate and treating the reaction mixture as inExample 28, there is obtained 0.8 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(5-hydroxyindan-1-yl)glycinehydrochloride as colorless amorphous powder.

NMR Spectrum (d⁶ -DMSO) δ: 1.10-1.70(6H, m, CH₃ x2), 1.75-3.30(8H, m,CH₂ x4), 3.7-4.30(5H, m, CH₂ x2+CH), 4.60-5.20(2H, m, CHx2),6.55-7.30(8H, m, Ph)

EXAMPLE 31

L-Alanyl-N-(5,6-dimethoxyindan-1-yl)glycine tert-butyl ester (4.0 g) isdissolved in 80 ml of ethanol, and 0.77 g of sodium acetate, 4.0 g ofacetate acid, 4.0 g of ethyl 2-oxo-4-phenyl-butyrate, 12 g of molecularsieve 3A and 6.0 g of Raney nickel are added. Thereafter, the reactionand treatment are carried out as in Example 2 to give 2.0 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(5,6-dimethoxyindan-1-yl)glycinetert-butyl ester as slightly yellow oil.

NMR Spectrum (CDCl₃) δ: 1.20-1.50(15H, m, CH₃ x5), 1.90-2.20(2H, m,CH₂), 2.50(2H, s, CH₂), 2.60-2.95(4H, m, CH₂), 3.80(3H, s, OCH₃),3.90(3H, s, OCH₃), 4.20(2H, q, J=7.0 Hz, CH₂), 5.40-5.60(1H, m, CH),6.80-6.90(2H, m, Ph), 7.25(5H, s, Ph).

Mass Spectrum m/e=568(M+), 495, 361, 308, 234.

EXAMPLE 32

N-(1-Ethoxycarbonyl-3-phenylpropyl-L-alanyl-N-(5,6-dimethoxyindan-1-yl)glycinetert-butyl ester (2.0 g) is dissolved in 10 ml of acetic acid, and 2 mlof 25% hydrobromic acid in acetic acid is added dropwise with icecooling. After allowing the mixture to stand at room temperature for 5minutes, 50 ml of ethyl ether is added to the reaction mixture,whereupon amorphous powder precipitates. This is collected by filtrationand dissolved in 10 ml of water. The solution is made alkaline withsodium hydrogen carbonate, and the insoluble matter is removed byextraction with ethyl ether. The aqueous layer is adjusted to pH 4.0with 10% hydrochloric acid and extracted with 100 ml of chloroform. Theextract is washed with water and dried, 1 ml of 20% ethanolichydrochloric acid is added, and the chloroform is distilled off underreduced pressure. The residue is dissolved in 2 ml of ethanol. On adding20 ml of ethyl ether, colorless amorphous powder precipitates.Collection of this precipitate by filtration gives 0.2 g ofN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(5,6-dimethoxyindan-1-yl)glycinehydrochloride as colorless powder.

NMR Spectrum (d₆ -DMSO) δ: 1.25(3H, t, J=8 Hz, CH₃), 1.40(3H, d, J=4.5Hz, CH₃), 3.75(3H, s, OCH₃), 3.80(3H, s, OCH₃), 6.80(1H, s, Ph),6.90(1H, s, Ph), 7.25(5H, s, Ph).

EXAMPLE 33

By the similar procedure to that in Example 32,N-(1-ethoxycarbonyl-3-phenylpropyl)glycyl-N-(indan-2-yl)glycinehydrochloride is obtained fromN-(1-ethoxycarbonyl-3-phenyl-propyl)glycyl-N-(indan-2-yl)glycinetert-butyl ester as colorless amorphous powder.

NMR Spectrum (d⁶ -DMSO δ: 1.30(3H, t, J=6 Hz, CH₃), 2.25(2H, m, CH₂),2.70(2H, m, CH₂), 2.90-3.20(4H, m, CH₂), 4.00-4.60(5H, m), 4.80-5.10(1H,m), 7.30(4H, s), 7.35(5H, s, Ph)

EXPERIMENT 1

Inhibitions of Angiotensin I Converting Enzyme (ACE) by the Compounds ofthis Invention.

EXPERIMENTAL METHOD

The experiment was conducted in accordance with a modification of themethod described by Cushman et al. [Biochemical Pharmacology, Vol. 20,1637(1971)]. That is, using hippuryl-L-histidyl-L-leucine(HHL) as thesubstrate, the ACE inhibitory activity was determined in terms ofpercent inhibition on the amount of hippuric acid produced by ACE whenthe present compound was added. A solution of the compound of thepresent invention dissolved in a 0.02 to 2% dimethyl sulfoxide-100 mMpotassium phosphate buffer solution (pH 8.3, containing 300 mM sodiumchloride) was added to 100 μl of ACE (protein concentration, 20 mg/ml)and 100 μl of 1.25 mM HHL. In this experiment, a potassium phosphatebuffer solution containing dimethyl sulfoxide at a concentration equalto that of the test solution was used as a control. After incubating thesolution at 37° C. for one hour, 150 μl of 1N hydrochloric acid wasadded to the solution to terminate the reaction. After 1 ml of ethylacetate was added, the solution was centrifuged at 3000 r.p.m. for 10minutes. A 0.5 ml aliquot was separated from the ethyl acetate layer anddried at a temperature below 50° C. under nitrogen gas streams. Theresidue was mixed with 5 ml of 1M aqueous sodium chloride and themixture was subjected to colorimetry at a wavelength of 228 nm.

TEST RESULT

The test results obtained with respect to the compounds of Examples 1,7, 8, 9 and 19 are shown in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        Example No.             Inhibitory Activity                                   of Tested   Concentration                                                                             on ACE                                                Compound    (μM)     (%)                                                   ______________________________________                                        1            1          87                                                                10          97                                                    7            1          91                                                                10          97                                                    8            1          69                                                                10          99                                                    9            1          72                                                                10          95                                                    19           1          95                                                                10          98                                                    ______________________________________                                    

EXPERIMENT 2

Effect of Present Compounds against Hypertensive Activity of AngiotensinI

EXPERIMENTAL METHOD

Male rats (Sprague-Dawley) weighing 250 g to 350 g which were fed underfree access to drinking water and feeds were used as experimentalanimals. The rats were anesthetized with intraperitoneal administrationof pentobarbital sodium (50 mg/kg) on the day before the test day and apolyethylene tube was inserted into each of the femoral artery formeasurement of blood pressure and the femoral vein for injection ofangiotensin I and II, and then the tubes were fixed.

On the test day, an average blood pressure in the control phase wasrecorded on an electric hemodynamometer (MP-4T model manufactured byNippon Koden, Japan) and thereafter angiotensin I and then angiotensinII were injected through the femoral vein at a dose of 300 ng/kg and 100ng/kg respectively, to measure the hypertensive activity. Then, 13.8μM/kg of the compound of this invention was administered orally as anaqueous solution or an aqueous gum arabic suspension, and 20, 60 and 120minutes after the administration, angiotensin I and II were injectedrepeatedly to trace hypertensive reactions. In calculating the percentinhibition to the hypertensive activity of angiotensin I, the percentinhibitory value was corrected based on the variation with time in thehypertensive reaction by angiotensin II.

TEST RESULT

The test results obtained with respect to the compounds of Examples 1,7, 9 and 15 are shown in Table 3 below

                  TABLE 3                                                         ______________________________________                                                   Percent Inhibition (%) against                                                Hypertensive Reaction by                                                      Angiotensin I                                                      Example No. of                                                                             After       After   After                                        Tested Compound                                                                            20 min.     60 min. 120 min.                                     ______________________________________                                        1            93          88      77                                           7            84          91      96                                           9            88          71      51                                           15           84          80      65                                           ______________________________________                                    

PREPARATION EXAMPLE

The compounds (I) of the present invention are used, for example, forthe treatment of hypertension in the following examples of formulation.

1. Tablets

    ______________________________________                                        (1)  N--(1-Ethoxycarbonyl-3-phenylpropyl)-                                                                 10      g                                             L-alanyl-N--(indan-2-yl)glycine                                               hydrochloride                                                            (2)  Lactose                 90      g                                        (3)  Corn Starch             29      g                                        (4)  Magnesium Stearate      1       g                                                                     130     g                                                               for 1000 tablets                                       ______________________________________                                    

The above ingredients (1), (2) and 17 g of corn starch are blended, andgranulated using a paste prepared from 7 g of corn starch. Five grams ofcorn starch and the ingredient (4) are added to the resulting granulesand the mixture is compressed by a tabletting machine to prepare 1000tablets having a diameter 7 mm each containing 10 mg of the activeingredient (1).

2. Capsules

    ______________________________________                                        (1) N--(1-Butoxycarbonyl-2-phenylethyl)-L-                                                                10       g                                            alanyl-N--(indan-2-yl)glycine                                                 hydrochloride                                                             (2) Lactose                 135      g                                        (3) Cellulose Fine Powder   70       g                                        (4) Magnesium Stearate      5        g                                                                    220      g                                                              for 1000 capsules                                       ______________________________________                                    

All of the above components are blended and encapsulated into GelatinCapsule No. 3 (IX Japanese Pharmacopoiea) to prepare 1000 capsules eachcontaining 10 mg of the active component (1).

3. Injectable Solution

    ______________________________________                                        (1)    N--[1-(S)--Carboxy-3-phenylpropyl)-L-                                                                10      g                                              alanyl-N--(indan-2-yl)glycine                                                 sodium salt                                                            (2)    Sodium Chloride        9       g                                       (3)    Chlorobutanol          5       g                                       (4)    Sodium Bicarbonate     1       g                                       ______________________________________                                    

All of the above ingredients are dissolved in 1000 ml of distilled waterand charged into 1000 brown ampules each containing 1 ml of thesolution. The ampules are replaced with nitrogen gas and sealed. Theentire preparation steps are conducted under sterile conditions.

What is claimed is:
 1. A compound of the formula: ##STR13## wherein R¹and R² independently represent hydrogen, hydroxyl or C₁₋₄ alkoxy, or R¹and R² jointly form C₁₋₄ alkylenedioxy,R³ is hydrogen or C₁₋₄ alkyl, R⁴is hydrogen, C₁₋₄ alkyl or amino-C₁₋₄ alkyl which is unsubstituted orsubstituted by acyl of the class consisting of C₂₋₄ alkanoyl, benzoyl,C₂₋₄ alkoxycarbonyl or benzyloxycarbonyl, R⁵ is hydrogen, C₁₋₄ alkyl orphenyl-C₁₋₄ alkyl which is unsubstituted or substituted by 1 to 3members of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, amino, nitro and hydroxyl,R⁶ is hydroxyl, C₁₋₄ alkoxy, amino or mono- or di-C₁₋₄ -alkylamino, andm and n each means 1 or 2,or a pharmaceutically acceptable salt thereof.2. A compound according to claim 1, wherein R¹, R² and R³ are hydrogen.3. A compound according to claim 1, wherein R⁴ is C₁₋₄ alkyl oramino-C₁₋₄ alkyl.
 4. A compound according to claim 1, wherein R⁵ isphenethyl.
 5. A compound according to claim 1, wherein R⁶ is hydroxyl orC₁₋₄ alkoxy.
 6. A compound according to claim 1, wherein m and n are 1.7. A compound of the formula: ##STR14## wherein R^(4') is hydrogen orC₁₋₄ alkyl,R^(5') is hydrogen, C₁₋₄ alkyl or phenyl-C₁₋₄ alkyl, andR^(6') is hydroxyl or C₁₋₄ alkoxy,or a pharmaceutically acceptable saltthereof.
 8. A compound according to claim 7, wherein R^(4') is C₁₋₄alkyl, R^(5') is phenyl-C₁₋₄ alkyl, and R^(6') is C₁₋₄ alkoxy.
 9. Acompound according to claim 8, which is an isomer having S configurationat each of the asymmetric carbon atoms to which the substituents R^(4')and R^(5') respectively are connected.
 10. A compound according to anyone of claims 1 to 9, wherein the pharmaceutically acceptable salt ishydrochloride.
 11. The compound according to claim 1, which isN-(1-ethoxycarbonyl-3-p-tolylpropyl)-L-alanyl-N-(indan-2-yl)gylcine. 12.The compound according to claim 1, which isN-[1-ethoxycarbonyl-3-(4-hydroxyphenyl)propyl]-L-alanyl-N-(indan-2-yl)glycine.13. The compound according to claim 7, which isN-(1-carboxy-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycine.
 14. Thecompound according to claim 7, which isN-(3-phenyl-1-propoxycarbonylpropyl)-L-alanyl-N-(indan-2-yl)glycine. 15.The compound according to claim 7, which isN-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-(indan-2-yl)glycine. 16.The compound according to claim 7, which isN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycine.17. The compound according to claim 7, which isN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycinehydrochloride.
 18. A pharmaceutical composition suitable for preventionor treatment of hypertension which comprises, as an active ingredient,an effective antihypertensive amount of a compound of the formula:##STR15## wherein R¹ and R² independently represent hydrogen, hydroxylor C₁₋₄ alkoxy, or R¹ and R² jointly form C₁₋₄ alkylenedioxy,R³ ishydrogen or C₁₋₄ alkyl, R⁴ is hydrogen, C₁₋₄ alkyl or amino-C₁₋₄ alkylwhich is unsubstituted or substituted by acyl of the class consisting ofc₂₋₄ alkanoyl, benzoyl, C₂₋₄ alkoxycarbonyl or benzyloxycarbonyl, R⁵ ishydrogen, C₁₋₄ alkyl or phenyl-C₁₋₄ alkyl which is unsubstituted orsubstituted by 1 to 3 members of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy,amino, nitro and hydroxyl, R⁶ is hydroxyl, C₁₋₄ alkoxy, amino or mono-or di-C₁₋₄ alkylamino, and m and n each means 1 or 2,or apharmaceutically acceptable salt thereof, and a pharmaceuticallyacceptable carrier, excipient or diluent therefor.
 19. A method forprevention or treatment of hypertension in a mammal, which comprisesadministering to said mammal an effective antihypertensive amount of acompound of the formula: ##STR16## wherein R¹ and R² independentlyrepresent hydrogen, hydroxyl or C₁₋₄ alkoxy, or R¹ and R² jointly formC₁₋₄ alkylenedioxy,R³ is hydrogen or C₁₋₄ alkyl, R⁴ is hydrogen, C₁₋₄alkyl or amino-C₁₋₄ alkyl which is unsubstituted or substituted by acylof the class consisting of C₂₋₄ alkanoyl, benzoyl, C₂₋₄ alkoxycarbonylor benzyloxycarbonyl, R⁵ is hydrogen, C₁₋₄ alkyl or phenyl-C₁₋₄ alkylwhich is unsubstituted or substituted by 1 to 3 members of halogen, C₁₋₄alkyl, C₁₋₄ alkoxy, amino, nitro and hydroxyl, R⁶ is hydroxyl, C₁₋₄alkoxy, amino or mono- or di-C₁₋₄ alkylamino, and m and n each means 1or 2,or a pharmaceutically acceptable salt thereof.
 20. A pharmaceuticalcomposition according to claim 18, wherein the active ingredient isN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycineor a pharmaceutically acceptable salt thereof.
 21. A method forprevention or treatment of hypertension according to claim 19 whereinthe compound isN-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanyl-N-(indan-2-yl)glycineor a pharmaceutically acceptable salt thereof.
 22. A method of treatinghypertension in a hypertensive mammal, which comprises administering adrug which upon administration to said mammal reduces said hypertension,said drug being of the formula:

    ROC--CR.sub.1 R.sub.2 --NR.sub.3 --CR.sub.4 R.sub.5 --CO--NR.sub.6 --CR.sub.7 R.sub.8 --COR.sub.9

wherein R is lower alkoxy, R₁ is aryl-lower alkyl, R₂, R₃, R₅, R₇ and R₈are hydrogen, R₄ is methyl, R₆ is indanyl and R₉ is hydroxy or apharmaceutically acceptable salt thereof.